U.S. patent application number 14/981324 was filed with the patent office on 2016-08-18 for light source unit emitting the three primary colors of light and projector including the light source unit.
This patent application is currently assigned to CASIO COMPUTER CO., LTD.. The applicant listed for this patent is CASIO COMPUTER CO., LTD.. Invention is credited to Osamu UMAMINE.
Application Number | 20160241820 14/981324 |
Document ID | / |
Family ID | 56622580 |
Filed Date | 2016-08-18 |
United States Patent
Application |
20160241820 |
Kind Code |
A1 |
UMAMINE; Osamu |
August 18, 2016 |
LIGHT SOURCE UNIT EMITTING THE THREE PRIMARY COLORS OF LIGHT AND
PROJECTOR INCLUDING THE LIGHT SOURCE UNIT
Abstract
To provide a light source unit whose overall size is relatively
small and a projector which incorporates the light source unit,
there is provided a light source unit including a first light
source device for emitting light in a first wavelength range, a
second light source device which is disposed on an axis of the
light in the first wavelength range and having a luminescent light
emitting area for emitting light in a second wavelength range by
receiving the light in the first wavelength range, and a third
light source device which is disposed on the axis of the light in
the first wavelength range so as to face the first light source
device for emitting light in a third wavelength range.
Inventors: |
UMAMINE; Osamu; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CASIO COMPUTER CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
CASIO COMPUTER CO., LTD.
Tokyo
JP
|
Family ID: |
56622580 |
Appl. No.: |
14/981324 |
Filed: |
December 28, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03B 21/204 20130101;
G03B 21/16 20130101; G02B 26/008 20130101; G03B 31/00 20130101;
H04N 9/3114 20130101; G03B 21/2033 20130101; G03B 21/2073 20130101;
H04N 9/3158 20130101 |
International
Class: |
H04N 9/31 20060101
H04N009/31; F21V 9/14 20060101 F21V009/14; G02B 26/00 20060101
G02B026/00; G02B 27/14 20060101 G02B027/14; G02B 5/30 20060101
G02B005/30; F21K 99/00 20060101 F21K099/00; G03B 21/20 20060101
G03B021/20 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 12, 2015 |
JP |
2015-024939 |
Claims
1. A light source unit comprising: a first light source device for
emitting light in a first wavelength range; a second light source
device which is disposed on an axis of the light in the first
wavelength range and having a luminescent light emitting area for
emitting light in a second wavelength range by receiving the light
in the first wavelength range; and a third light source device
which is disposed on the axis of the light in the first wavelength
range so as to face the first light source device for emitting
light in a third wavelength range.
2. The light source unit according to claim 1, further comprising:
a polarizing dichroic mirror which is disposed between the first
light source device and the second light source device for
reflecting the light in the second wavelength range and the light
in the third wavelength range and transmitting or reflecting the
light in the first wavelength range depending upon a polarized
direction thereof; and a quarter-wave plate which is disposed
between the polarizing dichroic mirror and the third light source
device.
3. The light source unit according to claim 1, wherein the second
light source device is made to be a luminescent material wheel
which is disposed between the first light source device and the
third light source device and which includes a wheel motor, and the
luminescent material wheel has the luminescent light emitting area
and a transmitting area, which transmits light, which are provided
end to end in a circumferential direction of the luminescent
material wheel.
4. The light source unit according to claim 2, wherein the second
light source device is made to be a luminescent material wheel
which is disposed between the first light source device and the
third light source device and which includes a wheel motor, and the
luminescent material wheel has the luminescent light emitting area
and a transmitting area, which transmits light, which are provided
end to end in a circumferential direction of the luminescent
material wheel.
5. The light source unit according to claim 1, wherein the first
light source device is a blue laser diode, the third light source
device is a red light emitting diode, and the luminescent light
emitting area of the second light source device is formed of a
green luminescent material layer.
6. The light source unit according to claim 2, wherein the first
light source device is a blue laser diode, the third light source
device is a red light emitting diode, and the luminescent light
emitting area of the second light source device is formed of a
green luminescent material layer.
7. The light source unit according to claim 3, wherein the first
light source device is a blue laser diode, the third light source
device is a red light emitting diode, and the luminescent light
emitting area of the second light source device is formed of a
green luminescent material layer.
8. The light source unit according to claim 4, wherein the first
light source device is a blue laser diode, the third light source
device is a red light emitting diode, and the luminescent light
emitting area of the second light source device is formed of a
green luminescent material layer.
9. The light source unit according to claim 1, wherein the third
light source device comprises a detection circuit for detecting an
electric current excited by the light in the first wavelength range
which is shone on to a light emitting surface thereof.
10. The light source unit according to claim 1, wherein the third
light source device has a dichroic mirror layer which reflects the
light in the first wavelength range and a diffusing layer on a
surface thereof.
11. The light source unit according to claim 1, wherein the second
light source device has a reflecting area which includes a
diffusing layer together with the luminescent light emitting area
and the transmitting area, the luminescent light emitting area, the
transmitting area and the reflecting area being provided end to end
in a circumferential direction of the luminescent material
wheel.
12. The light source unit according to claim 1, wherein the
polarizing dichroic mirror has a polarizing characteristic to
reflect P-polarized or S-polarized light in the first wavelength
range and transmit S-polarized or P-polarized light in the first
wavelength range.
13. The light source unit according to claim 1, wherein the
polarizing dichroic mirror is disposed so as to intersect axes of
the light in the first wavelength range, the light in the second
wavelength range and the light in the third wavelength range at an
angle of 45 degrees.
14. A projector comprising: the light source unit according to
claim 1; a display device for generating image light; a projection
side optical system for projecting image light emitted from the
display device on to a screen; and a projection control unit for
controlling the light source unit and the display device.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority under 35 U.S.C. 119 of Japanese Patent Application No.
2015-24939 filed on Feb. 12, 2015, the entire disclosure of which,
including the description, claims, drawings and abstract, is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a light source unit which
emits the three primary colors of light and a projector which
includes this light source unit.
[0004] 2. Description of the Related Art
[0005] In these days, data projectors are used on many occasions as
an image projection system which projects an image of a screen and
a video image of a personal computer, as well as images based on
image data which is stored on a memory card or the like on to a
screen. In these data projectors, light emitted from a light source
is collected to a micromirror display device called a DMD (Digital
micromirror Device) or a liquid crystal panel for displaying a
color image on the screen.
[0006] Conventionally, the mainstream of these data projectors has
been those which utilize a high-intensity discharge lamp as a light
source. In recent years, however, there have been developed and
proposed many projectors which utilize, as light sources, light
emitting devices or laser diodes, or organic ELs or luminescent
materials.
[0007] For example, the applicant of this patent application
proposed a projector which was made public in Japanese Unexamined
Patent Publication No. 2014-053844. This projector utilizes a light
source unit having a green light source device, a red light source
device and a blue light source device. The green light source
device includes an excitation light shining device and a
luminescent light emitting device. The red light source device and
the blue light source device utilize light emitting diodes.
[0008] In this light source unit, a first dichroic mirror is
provided between the excitation light shining device and the
luminescent light emitting device, so that the first dichroic
mirror transmits excitation light and light in the red wavelength
range from the red light source device and reflects light in the
green wavelength range from the luminescent light emitting device,
whereby the axis of the light in the red wavelength range which has
passed through the first dichroic mirror and the axis of the light
in the green wavelength range which has been reflected by the first
dichroic mirror are made to coincide with each other. Then, the
light in the green wavelength range and the light in the red
wavelength range whose axes are made to coincide with each other
are reflected by a second dichroic mirror. This second dichroic
mirror transmits light in the blue wavelength range from the blue
light source device, so that the axis of the light in the blue
wavelength range is made to coincide with the axes of the light in
the green wavelength rage and the light in the red wavelength
range. Then, the green light, red light and blue light whose axes
now coincide with one another are emitted from the light source
unit.
[0009] The application of this patent application also proposed a
projector which was made public in Japanese Unexamined Patent
Publication No. 2013-097233. This projector utilizes a light source
unit having an excitation light shining device which doubles as a
blue light source device, a luminescent light emitting device
having a luminescent material wheel including a diffuse
transmission portion and a red light source device utilizing a
light emitting diode.
[0010] In this light source unit, a first dichroic mirror is
provided between the excitation light shining device and the
luminescent light emitting device, so that the first dichroic
mirror transmits excitation light and light in the red wavelength
range from the red light source device and reflects light in the
green wavelength range from the luminescent light emitting device,
whereby the axis of the light in the red wavelength range which has
passed through the first dichroic mirror and the axis of the light
in the green wavelength range which has been reflected by the first
dichroic mirror are made to coincide with each other. Further,
light in the blue wavelength range is excitation light which is
emitted from the luminescent material wheel to a side opposite to a
side facing the excitation light shining device after having passed
through the diffuse transmission portion of the luminescent
material wheel, and this light in the blue wavelength range is
reflected by two reflection mirrors so that the axis thereof
becomes parallel to the axis of luminescent light. Then, the light
in the blue wavelength range is incident on a second dichroic
mirror for transmission therethrough. Thus, the axis of the light
in the blue wavelength range which has passed through the second
dichroic mirror is made to coincide with the axes of the light in
the red wavelength range and the light in the green wavelength
range whose axes are made to coincide with each other by the first
dichroic mirror and which have then been reflected by the second
dichroic mirror, whereby the red light, green light and blue light
whose axes coincide with one another are emitted from the light
source unit.
[0011] In addition, as described in Japanese Unexamined Patent
Publication No. 2014-134806, a light source is also proposed which
utilizes ultraviolet radiation as excitation light and a rotary
wheel to which a red luminescent material, a green luminescent
material and a blue luminescent material are applied.
[0012] In this light unit, ultraviolet radiation is shone on to the
rotary wheel on which the red luminescent material, the green
luminescent material and the blue luminescent material are disposed
along a circumferential direction of the rotary wheel as excitation
light so as to make the luminescent materials, which are situated
in positions where the excitation light is shone, luminous, whereby
light in the red wavelength range, light in the green wavelength
range and light in the blue wavelength range are emitted
sequentially from the rotary wheel.
[0013] As has been described heretofore, with the light source unit
including, as the three primary color sources, the luminescent
material which emits the light in the green wavelength range, the
red light source device made up of the light emitting diodes which
emits the light in the red wavelength range and the blue light
source device made up of the light emitting diodes which emits the
light in the blue wavelength range, the number of single-color
light source devices and the number of optical components for
making the optical paths of the single-color light rays emitted
from the single-color light source devices coincide with one
another so that the axes of the single-color light rays coincide
with one another are increased, making it difficult to realize a
small three primary color light source unit, which hence makes it
difficult to realize a small projector.
[0014] With the three primary color light source in which the
excitation light source device doubles as the blue light source
device, the number of single-color light source devices is reduced.
However, the number of optical components for making the optical
paths and axes of the luminescent light emitted from the
luminescent material wheel and the light in the blue wavelength
range, which has passed through the luminescent material wheel
while being diffused, coincide with each other is increased, also
making it difficult to realize a small three primary color light
source unit, which hence makes it difficult to realize a small
projector.
[0015] In addition, with the light source unit in which the light
in the red wavelength range, the light in the green wavelength
range and the light in the blue wavelength range are emitted from
the luminescent materials which are applied to the rotary wheel, it
is relatively easy to reduce the number of optical components and
to realize a small three primary color light source unit. However,
the luminescent light emitted from each of the luminescent
materials constitutes the red, green and blue light whose hue
shifts slightly relative to those of the three primary colors. In
particular, the red luminescent material is inferior in luminance,
color purity and luminous efficiency to LED, causing a problem that
with the red luminescent material, it is difficult to form a bright
projected image having a superior color reproduction
performance.
SUMMARY OF THE INVENTION
[0016] An object of the invention is to provide a light source unit
having a superior color reproduction performance and a relatively
small overall size and a projector including the light source
unit.
[0017] According to a first of the invention, there is provided a
light source unit having a first light source device which emits
light in a first wavelength range, a second light source device
which is disposed on an axis of the light in the first wavelength
range and which has a luminescent light emitting area which
receives the light in the first wavelength range to thereby emit
light in a second wavelength range, and a third light source device
which is disposed on the axis of the light in the first wavelength
range so as to face the first light source device.
[0018] According to a second aspect of the invention, there is
provided a projector having the light source unit according to the
first aspect of the invention, a display device which generates
image light, a projection side optical system which projects image
light emitted from the display device on to a screen, and a
projector control unit which controls the light source unit and the
display device.
BRIEF DESCRIPTION OF SEVERAL VIEWS of DRAWINGS
[0019] FIG. 1 is a perspective view showing an external appearance
of a projector according to a first embodiment of the
invention.
[0020] FIG. 2 is a functional block diagram of the projector
according to the first embodiment of the invention.
[0021] FIG. 3 is a schematic plan view showing an internal
construction of the projector according to the first embodiment of
the invention.
[0022] FIG. 4 is a front view of a luminescent material wheel and a
third light source device according to the first embodiment of the
invention.
[0023] FIG. 5 is an enlarged sectional view of a main part of a red
light emitting diode which functions as the third light source
device according to the first embodiment of the invention.
[0024] FIG. 6 is a front view of a luminescent material wheel and a
third light source device according to a third embodiment of the
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
First Embodiment
[0025] Hereinafter, an embodiment of the invention will be
described based on the accompanying drawings. FIG. 1 is an external
perspective view of a projector 10. When referred to in relation to
the projector 10 in this embodiment, left and right denote,
respectively, left and right with respect to a projecting
direction, and front and rear denote, respectively, front and rear
with respect to a direction towards a screen from the projector 10
and a traveling direction of a pencil of light emitted from the
projector 10.
[0026] The projector 10 has, as shown in FIG. 1, a substantially
rectangular parallelepiped shape. The projector 10 has a projection
port provided to a side of a front panel 12 which is a front side
panel of a projector casing. A plurality of inside air outlet ports
17 are provided in the front panel 12. Further, although not shown,
the projector 10 includes an Ir reception unit which receives a
control signal from a remote controller.
[0027] Additionally, a keys/indicators unit 37 is provided on an
upper case 11 of the projector casing. Disposed on this
keys/indicators unit 37 are keys and indicators which include a
power indicator, a projection switch key, an overheat indicator,
and the like. The power indicator informs whether a power switch
key or a power supply is on or off. The projection switch key
switches on and off the projection by the projector 10. The
overheat indicator informs of an overheat condition occurring in a
light source unit, a display device, a control circuit or the like
when they really overheat. In addition, the upper case 11 covers an
upper surface and part of a left side surface of the casing of the
projector 10, so that the upper case 11 is removed from a lower
case 16 when the projector 10 fails.
[0028] An input-output connector unit where a USB terminal, an
image signal input D-SUB terminal where analog RGB image signals
are inputted, an S terminal, an RCA terminal, a voice or sound
output terminal and the like are provided and various terminals
which include a power supply adaptor plug and the like are provided
on a back panel, not shown, of the casing. In addition, a plurality
of outside air inlet ports are formed in the back panel.
[0029] Next, a projector control unit of the projector 10 will be
described by the use of a functional block diagram shown in FIG. 2.
The projector control unit includes a control module 38, an
input-output interface 22, an image transforming module 23, a
display encoder 24, a display driver 26 and the like.
[0030] This control module 38 governs the control of operations of
circuitries within the projector 10 and is made up of a CPU, a ROM
which stores in a fixed fashion operation programs of various types
of settings, a RAM which is used as a working memory, and the
like.
[0031] Image signals of various standards that are inputted from
the input-output connector unit 21 are sent via the input-output
interface 22 and a system bus (SB) to the image transforming module
23 where the image signals are transformed so as to be unified into
an image signal of a predetermined format which is suitable for
display by the projector control unit. Thereafter, the image
signals so transformed are outputted to the display encoder 24.
[0032] The display encoder 24 deploys the image signals that have
been inputted thereinto on a video RAM 25 for storage therein and
generates a video signal from the contents stored in the video RAM
25, outputting the video signal so generated to the display driver
26.
[0033] The display driver 26 functions as a display device control
module and drives a display device 51, which is a spatial optical
modulator (SOM), at an appropriate frame rate in response to an
output of the image signal from the display encoder 24. Then, in
this projector 10, a pencil of light that is emitted from a light
source unit 60 is shone onto the display device 51 via a light
source side optical system, whereby an optical image (image light)
is formed by using reflected light reflected by the display device
51. The image so formed is then projected on to a screen, not
shown, for display thereon via a projection side optical system. A
movable lens group 235 of the projection side optical system is
driven by a lens motor 45 for zooming or focusing.
[0034] An image compression-expansion module 31 performs a
recording process of data compressing a brightness signal and a
color difference signal of the image signal to be sequentially
written on a memory card 32 that is a detachable recording medium
through operations using ADCT and the Huffman method.
[0035] Further, when in a reproducing mode, the image
compression-expansion module 31 reads out the image data recorded
on the memory card 32 and expands individual image data which make
up a series of dynamic images frame by frame. Then, the image
compression-expansion module 31 outputs the image data to the
display encoder 24 via the image transforming module 23 so as to
enable the display of dynamic images based on the image data stored
on the memory card 32.
[0036] Operation signals generated at the keys/indicators unit 37
which includes the main keys and the indicators which are provided
on the upper case 11 of the casing are sent out directly to the
control module 38. Key operation signals from the remote controller
are received by the Ir reception unit 35, and code signals are
demodulated by an Ir processing module 36 to be outputted to the
control module 38.
[0037] An audio processing unit 47 is connected to the control
module 38 via the system bus (SB). This audio processing module 47
includes a circuitry for a sound source such as a PCM sound source.
When in a projection mode and a reproducing mode, the audio
processing unit 47 converts audio data into analog signals and
drives a loudspeaker 48 to output loudly sound or voice based on
the audio data.
[0038] The control module 38 controls a light source control
circuit 41 which is configured as a light source control unit. This
light source control circuit 41 controls separately and
individually the emission of light in the red wavelength range,
light in the green wavelength range and light in the blue
wavelength range from the light source unit 60 so that
predetermined wavelength ranges of light required when an image is
generated can be emitted from the light source unit 60.
[0039] The control module 38 causes a cooling fan drive control
circuit 43 to detect temperatures through a plurality of
temperature sensors which are provided in the light source unit 60
so as to control the rotating speeds of cooling fans based on the
results of the temperature detections. The control module 38 also
controls the cooling fan drive control circuit 43 so that the
cooling fans continue to rotate even after the power supply to a
projector main body is turned off through a timer or the power
supply to the projector main body is turned off depending upon the
results of the temperature detections by the temperature
sensors.
[0040] Next, an internal construction of the projector 10 will be
described. FIG. 3 is a schematic plan view showing the internal
construction of the projector 10. Here, the light source unit 60 of
the projector 10 includes a first light source device 70, a second
light source device 100, and a third light source device 400. In
the projector 10, the light source side optical system includes
collective lenses 255, 113, 115, a light tunnel 114, a light axis
direction changing mirror 173 and a condenser lens 174. Further,
the projector 10 includes the projection side optical system
168.
[0041] As shown in FIG. 3, in the projector 10, the light source
unit 60 is disposed at a central portion, and the projection side
optical system 168 which includes a lens barrel 225 is disposed at
a left-hand side thereof. The display device 51 including DMDs is
disposed between the lens barrel 225 and the back panel 13. The
projector 10 includes further a main control circuit board, not
shown.
[0042] The light source unit 60 includes the first light source
device 70 which is disposed at a substantially central portion of
the casing of the projector 10 in relation to a left-to-right
direction of the casing. Further, the light source unit 60 includes
a luminescent material wheel device as the second light source
device 100, a red light source device 120 as the third light source
device 400, a polarizing dichroic mirror 141 and a quarter-wave
plate 111 on an axis of a pencil of light emitted from the first
light source device 70. Specifically, the luminescent material
wheel device as the second light source device 100 is disposed near
the front panel 12, and the red light source device 120 as the
third light source device 400 is disposed near the front panel 12.
The polarizing dichroic mirror 141 is provided between the first
light source device 170 and the second light source device 100, and
the quarter-wave plate 111 is disposed between the polarizing
dichroic mirror 141 and the second light source device 400.
[0043] The projector 10 includes a heat sink 191 for cooling the
display device 51 between the display device 51 and the back panel
13.
[0044] The first light source device 70 includes blue light sources
71 made up of solid-state light emitting devices and collimator
lenses 73. The blue light sources 71 are disposed so that their
optical axes are perpendicular to the back plate 13. The collimator
lenses 73 collect light emitted from the blue light sources 71
which are first light sources to a predetermined range for emission
therefrom. The first light source device 70 is a blue light source
device 300 and also doubles as an excitation light source device of
a green light source device 80.
[0045] In the first light source device 70, two blue laser diodes
are disposed side by side, and these blue laser diodes are
solid-state light emitting devices which emit light in the blue
wavelength range. Then, the collimator lenses 73 are disposed
individually on optical axes of the blue laser diodes which are the
blue light sources 71.
[0046] Then, the light source unit 60 includes a heat sink 81
between the first light source device 70 and the back panel 13. A
cooling fan 261 is disposed between the heat sink 81 and the back
panel 13, and this cooling fan 261 functions as a blower fan which
blows outside air into the casing towards the heat sink 81 as a
cooling medium, and the first light source device 70 is cooled by
the cooling fan 261 and the heat sink 81.
[0047] The green light source device 80 is made up of the second
light source device 100 which is the luminescent material wheel
device and the first light source device 70 which functions as the
excitation light source device. The second light source device 100
includes a luminescent material wheel 101, a wheel motor 110, and a
collective lens 112. The luminescent material wheel 101 is disposed
so as to be made parallel to the front panel 12, that is, so as to
be at right angles to an axis of light emitted from the first light
source device 70. The wheel motor 110 drives to rotate the
luminescent material wheel 101. The collective lens 112 collects a
pencil of light emitted from the luminescent material wheel 101 in
the direction of the back panel 13.
[0048] The luminescent material wheel 101 is made of a circular
metallic base material. A luminescent light emitting area 102 is
formed into an annular recess portion on the luminescent material
wheel 101, and this luminescent light emitting area 102 functions
as a second light source which uses light emitted from the blue
light sources 71 as excitation light to emit luminescent light
having a green wavelength range. Additionally, a surface of the
luminescent material wheel 101 which includes the luminescent light
emitting area 102 and which faces the first light source device 70
is mirror finished through silver deposition into a reflecting
surface which reflects light, and a layer of green luminescent
material is laid on this reflecting surface.
[0049] Light emitted from the first light source device 70 to be
shone onto the green luminescent material layer on the luminescent
material wheel 101 excites the green luminescent material laid on
the luminescent light emitting area 102. Luminescent light which is
emitted from the green luminescent material in every direction is
emitted directly towards the first light source device 70 or is
reflected by the reflecting surface of the luminescent material
wheel 101 to thereafter be emitted towards the first light source
device 70. A heat sink 130 and a cooling fan 135 are disposed
between the wheel motor 110 and the front panel 12, whereby the
luminescent material wheel 101 is cooled by them.
[0050] The third light source device 400 which is made up of the
red light source device 120 is disposed so that an axis of light
emitted therefrom substantially coincides with an axis of light
emitted from the first light source device 70. The red light source
device 120 includes a red light source 121 and is disposed so as to
face the first light source device 70 so that the collective lens
112 can be shared with the second light source device 100 to
collect light emitted from the red light source 121 into a
predetermined rage of light.
[0051] In this way, the blue light source device 300 which is the
first light source device 70, the green light source device 80
which is the second light source device 100 and the red light
source device 120 which is the third light source device 400 are
disposed so that an axis of light in the blue wavelength range
emitted from the blue light sources 71 of the first light source
device 70, an axis of light in the green wavelength range emitted
from the luminescent material wheel 101 and an axis of light in the
red wavelength range emitted from the red light source 121
substantially coincide with one another. The red light source 121
which constitutes a third light source utilizes a red light
emitting diode which is a solid-state light emitting device which
emits light in the red wavelength range.
[0052] In the light source unit 60, the polarizing dichroic mirror
141 is disposed between the first light source device 70 and the
second light source device 100 in such a way as to intersect light
emitted from the first light source device 70 and light emitted
from the second light source device 100 at an angle of 45 degrees.
The polarizing dichroic mirror 141 has a characteristic to reflect
all light in the green wavelength range, which is light in a second
wavelength range, emitted from the second light source device 100
and light in the red wavelength range, which is light in a third
wavelength range, emitted from the third light source device 400
and to transmit or reflect light in the blue wavelength range,
which is light in a first wavelength range, emitted from the first
light source device 70 depending upon a polarized direction
thereof.
[0053] In this embodiment, the polarizing dichroic mirror 141 and
the first light source device 70 are disposed so that P-polarized
light emitted from the first light source device is transmitted and
S-polarized light whose polarized direction differs 90 degrees from
that of the P-polarized light is reflected.
[0054] In the light source unit 60, the quarter-wave plate 111 is
disposed between the polarizing dichroic mirror 141 and the second
light source device 100. The quarter-wave 111 changes a polarizing
direction of light, which the quarter-wave plate 111 transmits,
from linear or plane polarization to circular polarization or from
circular polarization to linear or plane polarization.
[0055] FIG. 4 is a front view of the luminescent material wheel 101
and the red light emitting diode which makes up the third light
source device 400. The luminescent material wheel 101 has the
luminescent light emitting area 102 on the side facing the first
light source device 70 and has an annular transmitting area 104
which is formed by a cutout portion which is aligned
circumferentially with the luminescent light emitting area 102. The
transmitting area 104 does not have to be the cutout portion and
hence may be made up of a light transmitting material which is
formed in a circumferential direction of the luminescent light
emitting area 102. Additionally, the red light source 121 has a
light emitting surface 122 which emits light in the red wavelength
range and a glass cover 123 and is disposed on a rear surface side
of the luminescent material wheel 101 with respect to the first
light source device 70.
[0056] The luminescent light emitting area 102 is an area which
shines light in the green wavelength range, which is excited by
shining light in the blue wavelength range from the blue light
sources on to the green luminescent material, in the direction of
the blue light sources 71. The transmitting area 104 is an area
which transmits light in the blue wavelength range emitted from the
blue light sources 71 and light in the red wavelength range emitted
from the red light source 121.
[0057] FIG. 5 is an enlarged sectional view of a main part of the
red light emitting diode. As a general structure, the red light
source 121 has the light emitting surface 122 and the glass cover
123 which covers the light emitting surface 122. In this
embodiment, the light emitting surface 122 is formed into a
reflecting surface which reflects light in the blue wavelength
range.
[0058] An optical path of light in the blue wavelength range which
is emitted from the first light source device 70 which doubles the
blue light source device 300 and the excitation light source device
of the light source unit 60 will be described in detail
hereinafter. Light in the blue wavelength range which is light in
the first wavelength range emitted from the blue light sources 71
towards the front panel 12 passes through the polarizing dichroic
mirror 141. Namely, the blue light sources 71 are attached to the
casing of the projector 10 so that a polarizing plane of light in
the blue wavelength range from the blue light sources 71 which are
made up of laser diodes becomes such that light in the blue
wavelength range becomes P-polarized light in the blue wavelength
range in the polarizing dichroic mirror 141.
[0059] The P-polarized light in the blue wavelength range which has
passed through the polarizing dichroic mirror 141 passes through
the quarter-wave plate 111 and is changed from the P-polarized,
linearly polarized light to P-polarized, circularly polarized
light. The light in the blue wavelength range which has passed
through the quarter-wave plate 111 is collected by the collective
lens 122 and then passes through the transmitting area 104 of the
luminescent material wheel 101.
[0060] Then, the light in the blue wavelength range which has
passed through the transmitting area 104 is reflected in the
direction of the blue light sources 71 on the light emitting
surface 122 of the red light source 121 and passes again through
the quarter-wave plate 111, whereby the circularly polarized light
is again changed to linearly polarized light, resulting in
S-polarized light in the blue wavelength range. The S-polarized
light in the blue wavelength range is reflected on the polarizing
dichroic mirror 141 and is then emitted towards a left side panel
14.
[0061] The laser beams emitted from the blue light sources 71 and
reflected on the light emitting surface 122 are made into
non-coherent light as a result of being reflected on the light
emitting surface 122.
[0062] The wavelength of light in the blue wavelength range is
shorter than the wavelength of light in the red wavelength range,
and the optical energy of light in the blue wavelength range is
higher than the optical energy of light in the red wavelength
range. Consequently, in the event of light in the blue wavelength
range being shone on to the light emitting surface 122 to be
reflected thereon, a phenomenon reverse to the emission principle
is produced, and although it is minute, an electric current flows
in shining light in the blue wavelength range on to the light
emitting surface 122 of the red light source 121. Therefore, by
providing a separate circuit on the red light source 121 for
detection of the electric current, the red light source 121 can be
used to detect the rotation of the luminescent material wheel or
the output of light in the blue wavelength range.
[0063] Light in the green wavelength range emitted by the green
light source device 80 will be described in detail hereinafter.
When emitted from the first light source device 70 towards the
front panel 12, light in the blue wavelength range passes through
the polarizing dichroic mirror 141. Namely, the polarizing dichroic
mirror 141 transmits P-polarized light in the blue wavelength
range. The light in the blue wavelength range which has passed
through the polarizing dichroic mirror 141 passes through the
quarter-wave plate 111 to thereby be changed into circularly
polarized light. The light in the blue wavelength range which has
passed through the quarter-wave plate 111 is collected by the
collective lens 112 and is then shone on to the luminescent light
emitting area 102 of the luminescent material wheel 101.
[0064] The light in the blue wavelength range which has been shone
on to the luminescent light emitting area 102 excites the green
luminescent material in the green luminescent material layer,
whereby light in the green wavelength range is emitted from the
luminescent material wheel 101 towards the blue light sources 71.
The light in the green wavelength range which has been emitted is
collected by the collective lens 112. Then, the light in the green
wavelength range which is reflected in the direction of the blue
light sources 71 passes through the quarter-wave plate 111 to be
polarized, whereafter the light in the green wavelength range is
reflected on the polarizing dichroic mirror 141 to thereby be
emitted towards the left side panel 14.
[0065] An optical path of light emitted from the red light source
device 120 will be described in detail. When emitted from the red
light source 121 towards the back panel 13, light in the red
wavelength range passes through the transmitting area 104 of the
luminescent material wheel 101 and is thereafter collected by the
collective lens 112. Then, the light in the red wavelength range so
collected passes through the quarter-wave plate 111 to be
polarized, whereafter the light in the red wavelength range is
reflected on the polarizing dichroic mirror 141 to thereby be
emitted towards the left side panel 14.
[0066] The collective lenses 255, 113 which collect light emitted
from the light sources, the light tunnel 114 which uniformly
distributes the intensity of a pencil of light passing
therethrough, and the collective lens 115 which collects the light
emerging from the light tunnel 114 are disposed on a side of the
polarizing dichroic mirror 141 which faces the left side panel
14.
[0067] A solid optical glass rod which is a light guiding rod or an
array of microscopic lenses may be used in place of the light
tunnel 114 to realize light source light whose intensity is
uniformly distributed.
[0068] The condenser lens 174 shines effectively the light source
light reflected on the light axis changing mirror 173 on to the
display device 51. The heat sink 191 is disposed between the
display device 51 and the back panel to cool the display device
51.
[0069] The lens barrel 225 of the projection side optical system
168 has a group of lenses which projects "on" light, which is
reflected on the display device 51, onto a screen. A variable-focus
lens is used as this projection side optical system 168, and this
variable-focus lens has a zooming function by this variable-focus
lens being made up of a fixed lens group which is incorporated in
the lens barrel 225 and the movable lens group 235 which is
incorporated in a movable lens barrel, whereby making it possible
to perform a zooming adjustment or a focusing adjustment by a lens
motor causing the movable lens group 235 to be moved.
Second Embodiment
[0070] In the first embodiment, the light emitting surface 122 of
the red light source 121 which makes up of the red light source
device 120 is made into the reflecting surface configured to
reflect light in the blue wavelength range. However, there may be a
situation in which not the light emitting surface 122 of the red
light source 121 but the cover glass 123 of the red light source
121 is used as the reflecting surface which reflects light in the
blue wavelength range.
[0071] Namely, a dichroic coating treatment or the like is applied
to a surface of a cover glass 123 which covers a light emitting
surface 122 of a red light source 121 to form a reflecting surface
which reflects light in the blue wavelength range while
transmitting light in the red wavelength range. Additionally, a
diffusing layer is also provided on the reflecting surface so as to
diffuse light transmitted and light reflected.
[0072] As this occurs, not being limited to the red light emitting
diode (R-LED), a red laser diode can also be used as the red light
source 121.
[0073] In this embodiment, too, as with the first embodiment, light
in the blue wavelength range emitted from blue light sources 71
towards a front panel 12 passes through a polarizing dichroic
mirror 141 and then passes through a quarter-wave plate 111,
whereby the P-polarized, linearly polarized light in the blue
wavelength range is changed into P-polarized, circularly polarized
light in the blue wavelength range, which is collected by a
collective lens 112 to pass through a transmitting area 104 of a
luminescent material wheel 101.
[0074] Then, the light in the blue wavelength range which has
passed through the transmitting area 104 is reflected on the
surface of the cover glass 123 of the red light source 121 in the
direction of the blue light sources 71. Then, the light in the blue
wavelength range so reflected passes through the transmitting area
104 of the luminescent material wheel 101 again and is then
collected by the collective lens 112. The light in the blue
wavelength range so collected then passes through the quarter-wave
plate 111 again, whereby the circularly polarized light is changed
into linearly polarized light, resulting in S-polarized light in
the blue wavelength range. Then, the S-polarized light in the blue
wavelength range is reflected by the polarizing dichroic mirror 141
and is then emitted towards a left side panel 14.
[0075] When reflected on the surface of the cover glass 123, the
laser beams from the blue light sources 71 are formed into
non-coherent light by the diffusing layer formed on the surface of
the cover glass 123.
Third Embodiment
[0076] In the first and second embodiments, light in the blue
wavelength range is reflected on the light emitting surface 122 of
the red light source 121 which is disposed on the rear surface side
of the luminescent material wheel 101 or the cover glass 123 which
is provided on the surface of the red light source 121. However, in
a third embodiment, a reflecting area 103 is provided on a
luminescent material wheel 105 so that light in the blue wavelength
range is reflected by the reflecting area 103.
[0077] Namely, as shown in FIG. 6, a luminescent light emitting
area 102 and a reflecting area 103 are formed on a side of a
luminescent material wheel 105 which faces blue light sources 71,
and a transmitting area 104 is also formed annularly in such a way
as to be aligned circumferentially with the luminescent light
emitting area 102 and the reflecting area 103.
[0078] Similar to the first embodiment and the second embodiment,
the luminescent light emitting area 102 receives light in the blue
wavelength range from the blue light sources 71 to emit luminescent
light in the green wavelength range towards the blue light sources
71. The reflecting area 103 is an area which reflects light in the
blue wavelength range which is shone on to it towards the blue
light sources 71, and a diffusing layer is provided on a reflecting
surface of the reflecting area 103 to diffuse reflected light.
[0079] Similar to the first embodiment and the second embodiment,
the transmitting area 104 is an area which transmits light in the
red wavelength range emitted from red light source 121, and similar
to the first embodiment, a red light emitting diode is used for
this red light source 121.
[0080] In this third embodiment, too, light in the blue wavelength
range which is emitted from the blue light sources 71 towards a
front panel 12 passes through a polarizing dichroic mirror 141 and
then passes through a quarter-wave plate 111 to be collected by a
collective lens 112. The light in the blue wavelength range so
collected is then reflected in the direction of the blue light
sources 71 by the reflecting area 103 of the luminescent material
wheel 105 and is then collected by the collective lens 112 again.
Then, the light in the blue wavelength range which is reflected in
the direction of the blue light sources 71 passes through the
quarter-wave plate 111 again to be changed from circularly
polarized light to linearly polarized light, resulting in
S-polarized light in the blue wavelength range. The S-polarized
light in the blue wavelength range is reflected by the polarizing
dichroic mirror 141 to thereby be emitted towards a left side panel
14.
[0081] Similar to the first embodiment and the second embodiment,
light in the green wavelength range and light in the red wavelength
range pass through the quarter-wave plate 111 and are then
reflected by the polarizing dichroic mirror 141 to thereby be
emitted towards the left side panel 14.
[0082] It is noted that there may be a situation in which the
polarizing dichroic mirror 141 has a characteristic to reflect
P-polarized light and transmit S-polarized light.
[0083] Namely, an axis of light in the red wavelength range, which
is light in a third wavelength range from a third light source
device 400, is made to coincide with an optical axis of a light
tunnel 114. The surface of the luminescent material wheel 105 is
oriented in the direction of the light tunnel 114, and a first
light source device 70 is disposed near the front panel 12 or a
back panel 13. Then, the axis of light in the red wavelength range
is made to intersect an axis of light in the blue wavelength range,
which is light in a first wavelength range, at right angles in a
position where the polarizing dichroic mirror 141 is disposed.
P-polarized light in the first wavelength range emitted from the
first light source device 70 is reflected by the polarizing
dichroic mirror 141 to thereby be shone on to a second light source
device 100 and the third light source device 400.
[0084] As this occurs, the polarizing dichroic mirror 141 which
reflects P-polarized light and reflects S-polarized light is given
a dichroic characteristic to transmit light in a second wavelength
range emitted from the second light source device 100 and light in
the third wavelength range emitted from the third light source
device 400.
[0085] Thus, as has been described heretofore, in the embodiments
of the invention, the blue light sources 71 of the first light
source device 70 which emit light in the blue wavelength range, the
luminescent material wheel 101, 105 of the second light source
device 100 which has the luminescent light emitting area 102 which
receives light in the blue wavelength range from the blue light
sources 71 to emit light in the green wavelength range, and the red
light source 121 of the third light source device 400 which emits
light in the red wavelength range are disposed so that the axes of
blue light, green light and red light which are emitted
individually from the first, second and third light sources follow
the same linear path. This serves to line up the axes of blue
light, green light and red light, thereby making it possible to
simplify the optical path. The third light source device 400
utilizes the solid-state light emitting device or the LED which is
superior to a red luminescent material in luminance, color purity
and luminous efficiency, whereby it is possible to realize the
light source unit 60 and the projector 10 which can form a
projected image which is bright and superior in color reproduction
properties.
[0086] The second light source device 100 includes the luminescent
material wheel 105 and the wheel motor 110, and the luminescent
material wheel 105 has the luminescent light emitting area 102
which emits light in the green wavelength range and the
transmitting area 104 which transmits light, the luminescent light
emitting area 102 and the transmitting area 104 being arranged end
to end in the circumferential direction. This allows light in the
green wavelength range, light in the red wavelength range and light
in the blue wavelength range to be easily lined up with one another
to follow the same light axis for emission in the same direction
while simplifying the configuration of the second light source
device 100.
[0087] The blue light sources 71 of the first light source device
70 is made up of the blue laser diodes, the red light source 121 of
the third light source device 400 is made up of the red light
emitting diode, and the green luminescent material layer is formed
on the luminescent light emitting area 102 of the luminescent
material wheel 105 in the second light source device 100. This
makes it easy to emit light having high intensity together light in
the red wavelength range as light in the blue wavelength range and
light in the green wavelength range, thereby making it possible to
obtain efficient light source light.
[0088] The detection circuit is provided on the red light source
121 of the third light source device 400 to detect an electric
current which is excited by light in the blue wavelength range
emitted from the blue light sources 71 to be shone on to the light
emitting surface 122 of the red light source 121. This enables the
detection of whether or not the blue light sources 71 are turned on
or off and the rotational position of the luminescent wheel 105
without providing a sensor for detecting the rotational position of
the motor, thereby making it possible to fabricate the light source
unit 60 which is small in size and light in weight at low cost.
[0089] The third light source device 400 also includes the dichroic
mirror layer, which reflects light in the first wavelength range,
and the diffusing layer which are provided on the surface of the
red light source 121. This enables light in the blue wavelength
range to be reflected on the surface of the third light source
device 400 easily and efficiently.
[0090] Further, as shown in FIG. 6, there may be a situation in
which the reflecting area 103 which reflects light in the blue
wavelength range and the transmitting area 104 which transmits
light in the red wavelength range are provided on the luminescent
material wheel 105. This enables light in the blue wavelength range
to be reflected in such a way as to coincide with the emitting
position of light in the green wavelength range from the
luminescent light emitting area 102 and also enables the emitting
position of light in the red wavelength range to coincide with the
emitting position of light in the green wavelength range.
[0091] The polarizing dichroic mirror 141 is made to transmit
P-polarized or S-polarized light in the blue wavelength range while
reflecting S-polarized or P-polarized light in the blue wavelength
range and to reflect light in the green wavelength range and light
in the red wavelength range. This facilitates the emission of three
primary colors of light in the different direction from the optical
axes of the first light source device 70, the second light source
device 100 and the third light source device 400 whose axes are
lined up with one another or facilitates the emission of three
primary colors of light in the direction which coincides with the
axes of the second light source device 100 and the third light
source device 400 by changing the position of the first light
source device 70, whereby the light source unit 60 can easily be
built in the projector 10.
[0092] In the light source unit 60, the polarizing dichroic mirror
141 is disposed so as to intersect the optical axes of the first
light source device 70, the second light source device 100 and the
third light source device 400 at the angle of 45 degrees. This
makes the axis of light transmitted through the polarizing dichroic
mirror 141 and the axis of light reflected by the polarizing
dichroic mirror 141 differ 90 degrees from each other, facilitating
the matching of the axes of the different wavelength ranges of
light within the light source unit 60 and the matching of the axes
of the different wavelength ranges of light emitted from the light
source unit 60, whereby the light source unit 60 can be made small
in size.
[0093] The embodiments that have been described heretofore are
presented as illustrating the invention, and there is no intention
to limit the invention by the embodiments. These novel embodiments
can be carried out in other various forms, and various omissions,
replacements and modifications can be made to them without
departing from the spirit and scope of the invention. These
embodiments and their modifications are included in the spirit and
scope of the invention and are also included in the scope of
inventions claimed separately and equivalents thereof.
* * * * *